Improvement in screws



.` v UNITED STATES PATENT OFFICE.

J. A. AYRES, oF HARTFORD, CONNECTICUT.

I' `IMPROVEMENT IN SCREWS.

Specification forming part of Letters Patent N o. 38,141, dated April 14, 1863.

To all whom it may concern Be it known that I, J. A. AYRES, of Hartford, in the county of Hartford and State of Connecticut, have 'invented a new and useful Improvement in Screws and I do hereby declare that the following is a full, clear, and exact description of the saine, reference being had to the accompanying drawings, forming a part of this specification, in which- Figure 1 represents a side elevation ot my invention. Fig. 2 is a longitudinal central section of the same.

Similar letters ot' reference in both views indicate corresponding` parts.

This invention consists in the arrangement of a dovetailed slot in the head of a screw in such a manner that the edges ot' said slot at'-, ford a good and iirln hold to the screw-driver,

' and that said slot is not liable to wear out and let the screw-driver slip.

'Io enable those skilled in the art to make and use my invention, I will proceed to describe it with reference to the drawings.

The slots in ordinary screws are made with parallel sides, and lif the screw-driver is inserted the edges of said slot are soon rounded olil and the screw-driver is liable to slip, and

dered useless. It is, however, more particu larly the annoyance occasioned by the slipping of the screwdriver in the slots of ordinary screws which I have endeavored to obviate by my invention.

The sides of the slot a of my screw Aare inclined inwardly, so that a cross-section or end view of the slot presents the shape of adovetail,

as clearly shown in the drawings. This slot may be cut by means of two saws set at a slight angle, or by any other suitable device, and when properly eut it presents two sharp edges, b, which aiford a good hold tothe screw-driver, and which are not liable to wear away so as to render the screw useless.

It is obvious that this improvement is applicable to screws of any size and shape, the heads ot' which are. provided with a slot, and wherever applied it will be found that the annoyanee occasioned by the slipping of the screw-driver in the slots of ordinary screws is completely obviated by this apparently sim-I ple invention. r

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is-

A screw, A, with a dovetailed slot, a, as and for the purpose set forth.

J. A. AYRES.

Witnesses:

CHARLES WHITrLEsEY, J. W. OooMBs. 

